Participants had regular mammography; changes parallel drop in hormone therapy use after 2002

Thursday, November 11, 2010 (Last Updated: 11/12/2010)

THURSDAY, Nov. 11 (HealthDay News) -- Alongside a steep decline in the use of hormone therapy, incidence of invasive breast cancer and ductal carcinoma in situ fell in older women undergoing regular mammography in 2002 to 2006, according to research published online Nov. 8 in the Journal of Clinical Oncology.

Ghada N. Farhat, Ph.D., of the California Pacific Medical Center Research Institute in San Francisco, and colleagues analyzed data from 696,385 women aged 40 to 79 who underwent more than two million screening mammography exams between 1997 and 2006.

The researchers found that, after a steep decline in hormone therapy use in 2002, the incidence of invasive breast cancer fell significantly from 2002 to 2006 in women aged 50 to 69 and 70 to 79, but not in women aged 40 to 49. Rates of ductal carcinoma in situ fell after 2002 in women 50 to 69. In the two older groups, invasive ductal tumors fell significantly from 2002 to 2006. In 50- to 69-year-olds, rates of invasive lobular and estrogen receptor-positive cancer fell steadily from 2002 to 2005, but a rise in 2006 rendered these trends statistically nonsignificant.

"In conclusion, our study provides further support for the role of hormone therapy discontinuation in the decreasing incidence of invasive breast cancer, as well as ductal carcinoma in situ. Our results also hint to the possibility that the decrease in breast cancer may not persist; however, this finding certainly requires confirmation using longer monitoring of incidence rates," the authors conclude.